Apparatus for false twisting filaments of thermoplastics fibers



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5 Sheets-Sheet 1 Hmosnmo KIMURA ETAL m: 6 Mme/EH2 Jan. 27, 1970 APPARATUS FOR FALSE TWISTING FILAMENTS OF THERMOPLASTICS FIBERS Filed Feb. 16, 1968 3 m T N E A R Mu M K 0 m H S O m H (El-i) 90'] KATSUMI YASUZUKA AKIO KOSHIMO ATTORNEY:

Jan. 27, 1970 Hl-ROSHlRO KI'MU'RA ETAL APPARATUS FOR FALSE TWISTING FILAMENTS OF THERMOPLASTICS FIBERS 5 Sheets-Sheet 2 Filed Feb. 16, 1968 SNI'IOOO JO 31W :10 iNHIOIJJI-IOO I) INVENTORS. HIROSHIRO KIMURA AKIO KOSHIMO KATSUMI YASUZUKA ATTORNEYi United States Patent 3,491,524 APPARATUS FOR FALSE TWISTING FILAMENTS OF THERMOPLASTICS FIBERS Hiroshiro Kimura, Akin Koshimo, and Katsumi Yasuzuka, Kyoto, Japan, assignors to Nippon Rayon Co., Ltd., Kyoto, Japan Filed Feb. 16, 1968, Ser. No. 705,987 Claims priority, application Japan, Feb. 17, 1967, 42/ 10,197 Int. Cl. D0111 13/26; D02g 3/02 US. CI. 57-34 ABSTRACT OF THE DISCLOSURE An apparatus for false twisting of moving filaments by heating the filaments above their softening temperature prior to twisting as the filaments are passed over a pair of rollers by a heating means provided between the rollers, cooling means coupled to the filaments downstream of the heating means to cool the filaments below their 2nd order transition temperature, false twisting means for twisting the filaments between the heating and cooling means, and means to untwist the filaments after cooling into textured filaments.

This invention relates to apparatus, for false twisting filaments formed of thermoplastics fibers to produce treated filaments of excellent crimp and stretch characteristic during high speed production.

Hitherto, false twisting apparatus for thermoplastics fibers is achieved using an apparatus such as illustrated in FIG. 1, in which the fibers are twisted and thermoset simultaneously. With these apparatuses, treated fibers of excellent physical properties such as crimp characteristics, could not be obtained during high speed production. For the purpose of improvement, devices have been employed (1) to increase the capacity of heater or effective length of heater, (2) to force cool the twisted fiber after passing through heater by cooling with 'Water. No excellent textured fibers were obtained, nor sufficient high speed production were achieved by these improvements.

As the results of the proceeding researches to overcome these inferior areas of conventional false twisting apparatus, we are sure that sufficient thermosetting effects could not be obtained and textured filaments of excellent physical properties could not be produced in a high speed process, even if the eflfect of heater would be increased simply, and moreover forced cooling carried out, because the fibers would have extremely low thermoconductivity. We know that in the case of high treating speed, the twisted filaments would be passed through the false twisting apparatus in the state of being insufficiently cooled, and the crimped filaments would be extended by untwisting under high tension. Textured fibers of excellent properties could not be obtained, even if the hot twisted filaments were forcibly cooled to effect thermosetting in the conventional apparatus. The desired temperature of twisted filaments could not be reached, because the holding time in twisting zone is too short in the conventional false twisting mechanism and the plastic fibers have low thermoconductivity. A device using a longer heater may be considered as an effective method, but it is unfavorable mechanically in this machine, and the overall cost of the apparatus is high and control of temperature is difiicult.

The fact that plastics fibers have low thermal conductivity, is important and fairly long heating times are needed to heat plastics fibers to the desired temperature. However, the temperature lowering of thermoplastic fibers once raised, should be negligible due to the short holding time of practical methods for false twisting. From Claims I ice this point of view, it is impossible to speed up the process by mere increasing of the heater length or by forced cooling. And, it seems to be clear, that the thermosetting of filaments has a poor effect in a process wherein false twisting and thermosetting proceed simultaneously, as in conventional methods and apparatus. In addition, sufi'icient cooling can not be achieved in conventional apparatus, because the cooling zone is too short, even if forced cooling is employed. The holding time in heating and cooling is a very important factor in obtaining textured fibers of excellent physical properties by the false twist treatment of thermoplastic fibers which have low thermal conductivity.

Experimentally and theoretically, the relation between the temperature of heating or cooling and their times is given by the following:

T T log at (1) where T is the temperature of filament at the time t=0,

T is the temperature of heater in the case of heating and is the temperature of the cooling means (for example: room temperature) in the case of cooling,

T is the temperature at the time is t,

c is a constant concerned 'with the thermoconductivity and heat capacity of filament, and is the coefiicient of rate of cooling in the case of cooling and the coeflicient of rate of heating in the case of heating.

It is necessary that the temperature of twisted filament in the equation (1) must be lowered at least below the 2nd order transition temperature of the filament before the filament reaches the false twisting apparatus, after reaching the desired temperature in heater. Then, the filament must be untwisted. By conventional false twisting mechanism, these conditions are not satisfied in a high speed process over rn./.min. It is shown by our experiments that the conditions described above may be satisfied by increasing of effective length of heater and the temperature of twisted filament may be raised to near the desired temperature. The problems in cooling however, remain unsolved with conventional false twisting apparatus. For instance, in a high speed treating process, the temperature of twisted filaments which were once heated in process could not be lowered to 2nd order transition temperature by cooling with water, Dry Ice, etc., before reaching the false twisting apparatus for untwisting.

The results of this experiment are illustrated in FIG. 4. The experimental data show the relation between the temperature of treated filaments being passed through the heater in heating zone and the time. In this case, the friction false twisting treatment occurs at filament speed of m./min. using usual false twisting apparatus equipped with a 600 mm. length heater as illustrated in FIG. 1. According to the results, the temperature of heated filament is substantially lower as denier of the filament increases and on the other hand, the rate of cooling is smaller, that is cooling gradient is smaller, for the same treatment conditions. Since the filaments are not cooled to the 2nd order transition temperature before reaching the false twisting apparatus, they are untwisted at a considerably high temperature (60 to 80 C. for nylon 6 in this experiment) at extreme high speeds by the conventional methods. In this experiment, the length of cooling zone between heater and false twisting apparatus is 300 mm. (correspond to t=0.1 sec. in FIG. 4). The temperature of filament at t=0.1 sec. is over 60 to 80 C., and because of prescribed reasons, textured filaments of excellent crimp characteristic can not be obtained in high speed processes. The high speed treatment is even more difficult for the heavier denier filaments in conventional methods.

The results of experiments in cooling of heated filaments-show the relation between denier of filament and the coefficient of rate of cooling are illustrated in FIG. 5. Similar tendencies have been observed in the relation between denier and the coefficient of rate of heating, concerning experiments in heating of filaments. Even if the filaments are heated at higher temperature to increase the thermosetting effect, filaments of excellent crimp characteristic are not obtained because the temperature of filaments would be raised also at the untwisting zone since the temperature would be over 60 to 80 C. for nylon 6 with the filaments being untwisted by the high tension. This problem is important in friction type false twisting treatments at high speed as compared to the spindle type false twisting treatment. It is a necessary condition to achieve textured filaments of excellent crimp characteristics in friction type false twisting apparatus, that the turns per meter of the false twist be increased and the temperature of filament treated also be raised.

For that purpose, the friction between the filaments and the surface of friction device of the false twisting apparatus must be increased. As the result tensile strain applied to the filaments in twisting and untwisting zones will be increased. Therefore the filaments in the untwisting Zone would be at a temperature over the 2nd order transition temperature, and textured filaments of excellent crimp characteristics could not be obtained because of the prescribed reasons. The results of the experiments along this problem are shown in FIG. 6. The relation between the temperature of heater and the draft ratio in the twisting and untwisting zones and the crimp characteristic for filaments of 70d/ 24f nylon 6, treated at a filament speed of 150 m./min. with conventional friction type false twisting apparatus, are indicated.

FIG. 6 shows that the higher the temperature of heating and draft ratio, the lower the crimp characteristics of treated filament. Therefore, filaments of excellent crimp characteristic could not be obtained even if draft ratio were increased and the turns per meter of false twist increased and the temperature of the heater raised, because the heated filaments will be untwisted in a condition not cooled below 2nd order transition temperature.

The object of this invention is to provide an apparatus to obtain textured filaments of excellent crimp and stretch characteristics at extremely high speed.

Other important objects of the invention will be apparent from the following description.

According to the present invention, there is provided a process for false twisting of filaments of thermoplastic fibers to produce textured filaments, in which the filaments are heated above the softening temperature of the fila ments by passing them at least one time through heating zone over a pair of rollers with a heater being provided between the said rollers. The filaments are subsequently twisted by means of a false twisting device, and are subsequently cooled below the 2nd order transition temperature of the filaments and then untwisted by means of said false twisting device.

There is provided an apparatus for false twisting of filaments of thermoplastic fibers to produce the textured filaments which comprises a pair of rollers over which travel the filaments and a heater being provided between the said rollers to heat the filaments above at the softening temperature of the filaments prior to twisting. Cooling means cool the twisted filaments below the 2nd order transition temperature of the filaments, and a false twisting means untwists the filaments after cooling.

In the process indicated in this invention, it is necessary to heat filaments to be treated prior to twisting and it is also necessary to cool the filaments to a temperature below 2nd order transition point of it prior to untwisting. To perform the above mentioned treatment of filaments in extremely high speed operation, the filament must be heated prior to twisting, and must be cooled by cooling apparatus at the zone corresponding to the heating zone of conventional apparatus. This mechanism is therefore different from conventional apparatus.

In the drawings:

FIG. 1 is a schematic view of the prior art thermoplastic fiber filament treating apparatus;

FIG. 2 is a schematic view of the improved apparatus of the present invention;

FIG. 3 is a schematic view of a portion of the apparatus of the present invention in the form of a second embodiment;

FIG. 4 is a plot of treatment temperature versus time for filaments moving at different speeds through the conventional apparatus of FIG. 1;

FIG. 5 is a plot of the relationship between the coefficient of rate of cooling and denier for typical thermoplastic filaments;

FIG. 6a is a plot of crimp percentage against draft percentage for the treated filaments at various temperatures for filaments of 3200 T/ M under prior art treatment;

FIG. 6b is a similar plot to FIG. 6a for filaments of 3400 T/ M;

FIG. 60 is a similar plot to FIG. 6a for filaments of 3600 T/ M;

FIG. 7a is a plot of crimp percentage against draft percentage for filaments having false twists numbering 3200 T/M, processed according to the present invention at various temperatures;

FIG. 7b is a similar plot for filaments having false twists numbering 3400 T/ M;

FIG. 70 is a similar plot for filaments having false twists numbering 3600 T/ M;

FIG. 8a is a side elevation of one form of a filament cooler employed in the present invention;

FIG. 8b is a front elevation of the cooler of FIG. 8a;

FIG. 9a is a side elevation of another form of a filament cooler employed in the present invention;

FIG. 9b is a front elevation of the cooler of FIG. 9a;

FIG. 10a is a side elevation of yet another form of filament cooler employed in the present invention;

FIG. 10b is a front elevation of the cooler of FIG. 10a.

The process and apparatus for this invention may be explained with reference to the accompanying drawings. The apparatus being used for the preferred embodiment is illustrated in FIG. 2. The filaments Y being fed from pirm 1 pass tensioner 2 and then are heated by heater 5 to a desired temperature above the softening temperature of the filaments, passing once or more over a pair of spaced rollers 3-4. The filaments after being heated to above softening temperature, pass through nip roller 6 and are cooled by cooler 7 to a temperature below the 2nd order transition point and then pass through the false twisting device 8 and are lead to delivery roller 9 and wound on winding means 10. The filaments Y are given a false twist by false twisting device with the twist strain performed at the contact point of roller 4 and nip roller 6, that is, at nip point 11. The rollers 4 and 6 are closely positioned near cooling means 7.

Only one pair of rollers and a single heater are shown in FIG. 2, but the invention should not be limited by this embodiment. For instance, the rollers 3, 4 may have substituted therefor heated rollers, or a pair of heating plates 5 (shown in FIG. 3) may be used as the heating means. A device of spindle type or friction type, etc., may be used as a false twisting device, as at 8 in FIG. 2. In conventional false twisting apparatus of FIG. 1, a heater 5" for heating filaments is provided between false twisting device 8" and nip roller 6", but in the present invention cooling means 7 is provided in the corresponding zone, instead of the heater 5" in the conventional false twisting apparatus. The cooling means 7 may be water cooled pipe and the filament passageway provided in the pipe. The pipe is made from metal, such as, stainless steel, glass or synthetic resins.

The heated filaments are forced to contact the cooled block or tube, or may pass through the vicinity of cooling means 7. Continuous contact cooling of the heated filaments occurs with gas or liquid or solid used as cooling medium. Some examples for cooling apparatus 7 in FIG. 2, are shown in detail in FIG. 8 through FIG. 10b.

FIGS. 81: and 8b show metallic block 13 attached to cooling pipe 14 in which cooling water or other cooling medium is circulated. FIGS. 9a and 9b show a set of metallic blocks 13, 13 13 being separated, from each other to increase the cooling effect.

FIGS. 10a and 10b show example of air cooled blocks 13 13 13 13 cooled by being supported by an air 15 carrying tube 15 with the blocks contacting twisted filament Y.

In the present invention, in case of both nylon 6 and nylon 66 filaments, it is necessary to heat the filament at a temperature about 160 C. prior to twist and is necessary to cool the twisted filament at a temperature below 80 C. In case of polyethylene terephthalate filaments, it is necessary to heat the filament at a temperature of above 180 C. and is necessary to cool the filaments at a temperature of below 80 C.

The data of-the experiment, using the apparatus (shown in FIG. 2), is shown in FIG. 7, The relation between the temperature of heater, draft ratio in the twisting and untwisting zone and crimp characteristic of treated filaments are illustrated in FIG. 7. In this experiment the filaments of 70d/ 24 of nylon 6 were forced to make 6 turns on the spaced rollers, through the heating means which consisted of a pair of rollers of 100 mm. diameter and a heater of 600 mm. length, at the filament speed of 1000 m./min., twisted by a friction type false twisting device, and cooled with 1500 mm. length cooling means (shown in FIG. 8) in the zone where a heater would be provided in conventional false twisting device. The cooled filaments were untwisted by a false twisting device. From this diagram it is seen that crimp characteristic of the treated filaments are not lowered even if turns per meter of false twist are increased and even if the draft ratio is increased to raise the temperature of heater.

Even though the filaments were untwisted under high tension, textured filaments of excellent crimp characteristic are obtained, if the filaments, which were heated above softening temperature and then twisted, were cooled below the 2nd order transition temperature and transferred to the false twisting device in the state of being perfectly thermoset.

The process of this invention may be useful for any sort of filament, but is especially suitable for filaments formed of thermoplastic fibers, for example, fibers of polyamide,

25 polyester, polyacrylonitrile, polyolefine, etc.

The textured filaments produced by this invention may be favorably applied to woven and knitted fabrics and other end used.

The examples are as follows:

Example 1 Apparatus shown in Fig. 2

Comparison 1 Comparison 2 C 6 I D 1,50 1,500-.

"" E Stai ess block cooled Stainless block cooled by water (shown by water (shown in Fig. 8). in Fig. 8). F. Friction type Friction type Friction type Friction type. G D/24F Nylon 6 D/34F polyethy- 70D/24F Nylon 6--..-. 75D/34F Polyethylene phthalate. lene terephthalate. H 1,000 850 200 145. II--." 70 188.-

J 178 205 180 215. K Between 3 and Between 3 and 4. Between 6 and 9:5 Between 6 and 9:4.5.

Between 4 and 9'9 Between 4 and 9:8

. 9019: R. Fine crimp and ex- Coarse crimp and HI celllept stretch poor stretch ability. poor bulky.

""" 2. l l y.

5-.-... voluminous, excellent High bulky Poor stretch ability Poor elasticity and stretch ablllty. and poor elasticity. poor voluminous.

No spot.

NOTES:

I. Specification of apparatus:

A. Diameter of roller 3, 4. 1%. Length of heater (mm.

Passing turn number of filaments in the heating means. 11):. Length of cooling zone (mm.)

. Cooling means.

F. False twisting device II. Conditions of operation:

G. Filament.

H. Speed of filament (m./min.)

I. Temperature of roller 3, 4.

J. Temperature of heater (C.).

K. Draft ratio (percent).

L. Turns per meter of false twist.

. Properties of textured filament:

M. Tensile strength (g./d.).

T. Dyeing property:

Disperse dyes Acid dyes Metal complex dyes U. Production of treated filaments to a spin per day, kg.

7 REMARKs:

The values of measurement elongation and elasticity are decided by the measurements as follows:

Elongation= X 100 Elasticir =gs x100 where:

a=length of filament loaded with 2 mg./d. after holding of 2 min.

b=length of filament loaded with g./d. after holding 1 min.

c=same measurement as in a being measured after b in sequence.

Latent elongation crimp and latent elasticity crimp are the value of elongation and elasticity being measured after treatment that the filaments are treated in water of 100 C. for 30 min, without tension.

What is claimed is:

1. An apparatus for false twisting of moving filaments of thermoplastic fibers to produce textured filaments, comprising a heating means including a pair of spaced rollers about which the filaments are wrapped and a heater provided between the said rollers to heat the filaments above the softening temperature of the filaments prior to twisting, coolin means operatively coupled to said filaments downstream of said heating means to cool said filaments below their 2nd order transition temperature, false twisting means to twist said filaments between said heater and said cooling means and to untwist the filaments after cooling and means to preclude any twist extending into said heating means.

2. An apparatus as claimed in claim 1 wherein said rollers are heated.

3. An apparatus as claimed in claim 1 wherein said heater comprises heating plate in contact with the filament turns.

4. An apparatus as claimed in claim 1 wherein said false twisting means are of the friction type.

5. An apparatus as claimed in claim 1 wherein said false twisting means are of the spindle type.

6. An apparatus as claimed in claim 1 wherein said cooling means comprises a water cooled pipe including a filament passage carried by the pipe.

7. An apparatus as claimed in claim 6 wherein said pipe is made from metal.

8. An apparatus as claimed in claim 6 wherein said pipe is made from glass.

9. An apparatus as claimed in claim 6 pipe is made from synthetic resins.

10. An apparatus for false twisting of moving filaments of thermoplastic fibers to produce textured filaments, comprising a heating means including a pair of spaced rollers about which the filaments are wrapped and a heater provided between the said rollers to heat the filaments above the softening temperature of the filaments prior to twisting, cooling 'means operatively coupled to said filaments downstream of said heating means to cool said filaments below their 2nd order transition'temperature, and false wherein said "twisting means to twist said filaments between said heater and said cooling means and to untwist the filaments after cooling and wherein the roller nearest the cooling means is closelyspaced to a nip roller, with the filaments sandwiched therebetween. 4

References Cited UNITED STATES PATENTS 3,166,881 1/1965 Servage 5734 3,289,400 12/1966 Scragg 57-157 XR 3,367,006 2/1968 Mattingly 57 34 XR 2,863,280 12/1958 Ubbelohde 57 157 3,017,685 1/1962 Heberlein 57 157 XR 3,101,990 8/1963 Heighton 28 62 XR 3,237,392 3/1966 Crouzet s7-34 XR 3,270,492 9/1966 Fitton et al 57-34 XR 3,293,838 12/1966 Butsch -2 57-34 3,352,959 11/1967 Hoyer et al. 28--72 XR 3,001,355 9/1961 Evans 57-34 3,382,555 5/1968 Smootz 28 62 FOREIGN PATENTS 1,064,193 8/1959 Germany.

DONALD E. WATKINS, Primary Examiner US. Cl. X.R. 57-157 

